Combined current transformer and disconnect switch



H. THOMMEN 2,793,330

NNECT swrwcn May 21, 1957 COMB-INED-CURRENT TRANSFORMER AND DISCO Filed April 5, 1955 WW J 531: $5

United States Patent COMBINED CURRENT TRANSFORMER AND DISCONNECT SWITCH Hans Thommen, Baden, Switzerland, assignor to Aktiengesellschaft Brown, Boveri & Cie, Baden, Switzerland, a joint-stock company Application April 5, 1955, Serial No. 499,415

Claims. (Cl. 317--157.6)

The present invention relates to electrical apparatus and in particular to high-voltage switching and current measuring apparatus designed for use in outdoor type transformer stations.

The general object of this invention is to effect an economy in cost of production and saving in space by combining, structurally, a current transformer of the single pillar type with a disconnect switch of the type wherein the disconnect blade in disconnecting a circuit moves longitudinally of itself rather than pivotally. More particularly, this objective is brought about through the use of a tubular guide which is inserted in the vertical lead-in insulator sleeve portion of the current transformer, and a rod, preferably of conductive material, which is adapted to be raised and lowered in the tube. The upper end of the rod when raised is adapted to make contact with the high voltage line, and the lower end of the rod, when in such position, establishes contact with one of the leads to the primary Winding of the current trans former, thus establishing a circuit for flow of current to the primary winding from the high voltage line. When the rod is lowered, the upper end thereof breaks its connection with the high voltage line thus disconnecting the current transformer from the line and hence also the branch power line circuit with which the primary winding of the current transformer is series connected. Preferably the movable rod is constructed as a rack and the teeth of the rack are adapted to be engaged by a pinion gear that can be driven in either direction from a reversible motor thus enabling the rod to be raised and lowered dependent upon the direction of rotation of the drive pinion.

The foregoing as well as other objects and advantages inherent in the invention will become more apparent from the following detailed description of an exemplary embodiment and the accompanying drawings in which Fig. 1 is a view in vertical central section of the combined current transformer and disconnect switch showing the disconnect switch rod in its lowered position while Fig. 2 is a view in elevation of the same apparatus taken at 90 from that of Fig. 1 and showing the disconnect rod in its raised position.

With reference now in particular to the drawings, the current transformer portion of the apparatus is essentially conventional being comprised of a base I mounted on casters or wheels 2 for ease in transport from one position to another. A housing 3 is supported upon the base, and within this housing is supported the lower coil portion of the primary winding 4 of the current transformer which is protected by an outer sheath 5 of insulation. interlinked with the transformer primary winding 4 is an annular secondary Winding shown schematically at 6. Within the upper tubular portion 5a of the insulating sheath for the primary winding is inserted a tubular guide 7 of electrically conductive material which is connected at its lower end to one end of the loop portion of the primary winding 4 and at its upper end to a conductor 10 which extends upwardly to a spring type contactor 11 2,793,330 Patented May 21, 1957 which engages and hence makes electrical contact with a rod 12 which is adapted to be raised and lowered within the tubular guide 7, the rod 12 constituting the reciprocatable blade member of the disconnect switch. To this end, the upper end of rod 12 terminates in two sets of confronting contact fingers 13, 13 which embrace and engage a fixed contact head 14 secured along the high voltage conductor 15 whenever the rod 12 is raised to the position shown in Fig. 2. The rod 12 can be made to raise and lower by various means but in the present embodiment one side of rod 12 is made as a rack having a succession of teeth 16 in mesh with a pinion gear portion of a combined pinion gear and sprocket 17 which is journalled for rotation within a cap 18 at the top of an insulator column 19 surrounding the tubular insulator sheath 5a, the guide tube 7 and the rod 12, the lower end of the insulator column 19 resting upon the top face of housing 3. The spring contactor 11 which rides in contact with rod 12 is supported by the cap 18 and the rod 12 of course extends upwardly through a hole in the top of the cap. The cap 18 also includes a laterally extending portion 18a in which is supported the upper end of a second upstanding insulator column 21 extending generally parallel with the insulator column 19, the lower end of column 21 being supported upon the top face of housing 3. A motor 22 outside the housing 3, the motor being shown generally schematically, ha its drive shaft connected through bevel gearing 23 within the casing to a vertical shaft 24 which is journalled for r0- tation within the insulator column 21. The upper end of shaft 24 terminates in a bevel gear 25 which meshes with a combined bevel gear and sprocket 26, and the sprocket part is coupled to the sprocket part of the combined pinion and sprocket element 17 by means of a chain 27. Motor 22 is reversible and preferably controllable from a remote location by means not shown. Hence the disconnect rod 12 can be raised or lowered dependent upon the direction of motor 22.

The other end of the loop portion of primary winding 4 is connected by means of an insulated conductor 23 to the high voltage branch circuit output terminal 29.

Consequently, it will now be evident that when the disconnect switch rod 12 occupies the lowered position shown in Fig. 1, the branch circuit terminal 29 is disconnected trom the line 15 and so is also disconnected the primary Winding 4 of the current transformer, When the rod 12 is raised to the position shown in Fig. 2, the upper end of this rod makes contact with the line 15, the lower end is still in contact with contactor 11 and hence a circuit from the line 15 is established through rod 12, contactor 11, conductor 10 and through primary winding 4 of the current transformer to the branch circuit output terminal 29.

As indicated in the introduction, the advantages of the improved, combined construction of current transformer and disconnect switch, are less cost than what would be involved in making up each as an independent unit, and less space occupied at the station.

In conclusion, it will be understood that while the time going embodiment is possibly to be preferred, various modifications in the construction and arrangement of parts may be made without departing from the spirit and scope of the inventive concept as defined in the appended claims.

I claim:

1. A combined current transformer and disconnect switch for high voltage lines comprising interlinked primary and secondary windings, an insulating sheath enclosing said primary winding, said sheath including an upwardly extending tubular portion, a pair of leads extending from said primary winding upwardly through the tubular portion of said sheath, an upright tubular guide supported within said tubular portion of said insulating sheath, an upright electrically conductive rod mounted within and movable longitudinally along said tubular guide, means maintaining continuous electrical contact between said rod and one of said leads to said primary winding, a contact member carried by the upper end of aid rod adapted to engage a complementary contact member carried by said high voltage line when said rod occupies its raised position, and means for raising and lowering said rod thereby to make and break the connection between said contact members as said rod is raised and lowered.

2. A combined current transformer and disconnect switch as defined in claim 1 wherein said rod is also constituted as a rack gear and said means for raising and lowering said rod comprises a pinion gear meshed with the teeth of said rack gear and means for rotating said pinion gear in either direction.

3. A combined current transformer and disconnect switch as defined in claim 1 wherein said means maintaining continuous electrical contact between said rod and one of the leads of the transformer primary comprises a stationary contactor along and in contact with which said rod slides.

4. A combined current transformer and disconnect switch as defined in claim 1 wherein said upright tubular guide is made from electrically conductive material and said guide is electrically connected to one of said leads to said primary winding.

5. A combined current transformer and disconnect switch for high voltage lines comprising a lower casing, a tubular insulator column upstanding upon said casing, interlinked primary and secondary windings of said transformer disposed in said casing, said primary winding including a pair of lead-in conductors and a surrounding insulating sheath extending upwardly through said insulator column, an upright tubular guide supported within said insulating sheath, an upright electrically conductive rod mounted within and movable longitudinally along said tubular guide, means maintaining continuous electrical contact between said rod and one of said lead-in conductors, said rod being also constituted as a rack gear, a second tubular insulator column upstanding upon said casing, a rotatable drive shaft extending upwardly through said second insulator column, a motor arranged in driving connection with the lower end of said shaft, a pinion gear meshed with the teeth on said gear rack, a driving connection between the upper end of said shaft and said pinion gear for rotating said pinion gear to raise and lower said rod and a contact member carried by the upper end of said rod adapted to engage a complementary contact member carried by said high voltage line when said rod occupies its raised position.

References Cited in the file of this patent UNITED STATES PATENTS 

